Lane Narrowing

Roadway lane narrowing may help to reduce vehicle speeds along a roadway section and enhance movement and safety for bicyclists as well as pedestrians. Lane narrowing is best used where motor vehicle speeds are low to encourage shared lane travel and prevent motorists from attempting to pass bicyclists within the same lane if there is insufficient width. Another use would be to gain space to stripe a bicycle lane or paved shoulder where motor vehicle speeds and volumes are higher.

Lane narrowing can be achieved in several different ways depending on the type and scope of a project. During all projects there are opportunities to reduce lane widths to the recommended minimums (see AASHTO Green Book for further information):

9 feet lanes on rural roadways

10 feet for most vehicular travel lanes

10 feet for turn lanes

11 feet for lanes to accommodate large volumes of trucks, buses, or larger vehicles (typically where volumes of large vehicles are greater than 8 percent)

With the additional space created from narrowing travel lanes, space can be redistributed for the following uses:

Evaluate whether narrowing may encourage traffic to divert to local neighborhood streets.

On roadways with excess vehicle capacity, a reduction in the number of travel lanes may be feasible (see lane reduction).

Estimated Cost

Simply adding striped shoulders or on-street bike lanes can cost as little as $0.15-0.20 per linear foot, or approximately $750 to $1,000 per mile. Restriping can cost between $5,000 and $30,000 per mile, depending on how many lanes must be removed, and whether bike lanes are added. Typically the number of striping needed for a block puts the cost between $1,000 and $3,000 per block. If the road must be restriped or reconfigured, the cost is closer to $12,500 per block. Adding a raised median, widening a sidewalk, and adding improvements such as landscaping or curb extensions can significantly increase the cost.